The local environment of Cr3+ impurities in normal and x-rays irradiated carbon doped ruby: An electron paramagnetic resonance (EPR) study

•Cr3+ doped normal and x-rays irradiated α-Al2O3 are studied by EPR at room temperature.•Spin Hamiltonian (SH) parameters have been obtained for each sample.•Theoretical confirmation of the experimental findings has been carried out.

Local environment of substitutional paramagnetic point defect (impurity) in normal and x-ray irradiated commercially available α-Al2O3:C samples (commercial product of Landauer, Inc.) has been studied by using the electron paramagnetic resonance (EPR) technique at room temperature. In both samples the EPR spectra showed strongly angular dependent behavior. The zero-field splitting (ZFS) parameters (ZFSPs) have been determined for substitutional Cr3+ centers. The observed additional EPR signals for x-ray irradiated sample were attributed to another center with different spin Hamiltonian (SH) parameters. In addition to the experimental findings, the ZFSPs and the local structure of the Cr3+ ions were theoretically determined using superposition model (SPM) calculations.